RC4 is an insecure cryptographic stream cipher that is known to have multiple critical security flaws that render it essentially useless. RC4 was primarily used in the Wi-Fi security protocol WEP (wired equivalent protocol) and as a cipher in TLS ((Transport Layer Security) used in web security for HTTPS) before significant vulnerabilities were discovered in 2001 and 2013 respectively. The RC4 cipher was first designed in 1987 by Ron Rivest of RSA Security. The algorithm remains proprietary, although it was reverse-engineered and leaked in 1994, to avoid copyright claims the algorithm is sometimes also called ARC4 (Alleged Rivest Cipher 4).
RC4
